#include<stdio.h>
#include<string.h>
int main()
{
	char s1[100],s2[100];
	while(scanf("%s%s",&s1,&s2)!=EOF)
	{
		int i,j;
		int len1=strlen(s1);
		int len2=strlen(s2);
		strcat(s1,s2);
	for(i=0; i<len1+len2-1; i++)
     for(j=0; j<len1+len2-i-1; j++)
        if(s1[j+1]<=s1[j])
        {
	        int t=s1[j];
	        s1[j]=s1[j+1];
	        s1[j+1]=t;
        }
    puts(s1);
	}
	return 0;
}
